NEW YORK (Reuters Health) – The incidence of second primary colorectal cancers is high, suggesting a failure in the management of these patients, according to a report in the February 19th issue of the Annals of Internal Medicine.
Dr. Daniel G. Haller from the University of Pennsylvania School of Medicine, Philadelphia, and colleagues evaluated 3278 patients who had resected stage II or stage III colon cancer. The subjects were participants in the National Cancer Institute Intergroup 0089, a multicenter, international study of adjuvant 5-fluororuracil-based chemotherapy for localized colon cancer.
Follow-up surveillance guidelines for study patients included colonoscopy or barium enema plus sigmoidoscopy performed 6, 12 and 18 months after surgery, and then annually. However, physicians could opt for surveillance every 18 to 24 months after the 6-month screen.
Over 15,345 person-years of follow-up, there were 42 second primary invasive colon cancers diagnosed, the researchers report. This finding yielded an incidence rate of 274 cases per 100,000 person-years. The cumulative incidence at 5 years was 1.5%, Dr. Haller's team calculated.
Compared with the general population, the incidence ratio was 1.6. And compared with subjects from the National Polyp Study, which included patients who had undergone frequent colonoscopy and polypectomy due to a history of adenomatous polyps, the incidence ratio was 6.8, the investigators note.
"Our study does not address whether more frequent surveillance would have decreased the incidence of second primary colorectal cancer or led to earlier diagnosis," Dr. Haller and colleagues comment.
"However, we believe our data show that in practice, despite surveillance, rates of second primary cancer will remain at least as high as rates of first primary cancer in the general population and significantly higher than would be expected from the National Polyp Study."
"A significant proportion of second primary colorectal cancers represents a failure in patient management at several possible levels," Drs. Paul J. Limburg and David A. Ahlquist from the Mayo Clinic, Rochester, Minnesota, comment in a journal editorial.
However, they add, "for now, adherence to the existing consensus guidelines for postoperative surveillance seem warranted until convincing evidence to support alternative strategies becomes available."